Method for producing a high-quality insulation for electric conductors or conductor bundles of rotating electrical machines by means of thermal spraying

Abstract

The process according to the invention discloses production of a high-quality insulation for conductors or conductor bundles. In this process, internal corona-discharge protection, insulation and external corona-discharge protection are all applied to the conductor or conductor bundle in successive steps by means of thermal spraying. The application thickness per spraying run is up to 0.2 mm, thus ensuring that the layer is free of defects and therefore avoiding partial discharges. Moreover, the ability to withstand thermal loads is considerably improved by the use of high-temperature plastics with fillers comprising inorganic materials as coating powder.

What is claimed is:  
     
       1. A process for producing a high-quality insulation for conductors or conductor bundles, comprising the steps of: 
       (S 1 ) mounting a conductor or conductor bundle which is to be coated on a rotation and holding device;  
       (S 2 ) heating the conductor or conductor bundle to a predetermined substrate temperature;  
       (S 3 ) orienting the conductor or conductor bundle position with a flat side perpendicular with respect to a spray gun;  
       (S 4 ) thermal spraying a liquid or plastic internal corona-discharge protection onto the heated substrate from a coating powder, the application layer thickness being approximately 0.05 to 0.2 mm,  
       (S 5 ) rotating the conductor or conductor bundle, so that a further flat side of the conductor or conductor bundle is oriented perpendicular to the spray gun, and then a repeating steps S 3  and S 4  and repeating this step S 5  until all the sides of the conductor or conductor bundle have been coated;  
       (S 6 ) changing the coating powder into an insulant-filled powder;  
       (S 7 ) coating the conductor or conductor bundle with the insulant-filled powder in at least one pass on all sides of the conductor or conductor bundle as described in steps S 3  to S 5 ;  
       (S 8 ) carrying out steps S 6  and S 7  using a coating powder for an external corona-discharge protection; and  
       (S 9 ) cooling the coated conductor or conductor bundle and removing it from the rotation and holding device.  
     
     
       2. The process as claimed in  claim 1 , wherein the conductor or conductor bundle comprises a conductor bar, a transposed bar, or a coil. 
     
     
       3. The process as claimed in  claim 1 , further comprising: 
       (S 0 ) prestrengthening the conductor or conductor bundle by internal adhesive bonding of the conductors or by winding a tape around said conductor or conductor bundle.  
     
     
       4. The process as claimed in  claim 1 , wherein said coating powder comprises high-temperature plastics with fillers comprising inorganic material. 
     
     
       5. The process as claimed in  claim 4 , wherein said high-temperature plastics comprise high-performance thermoplastics selected from the group consisting of polyether ether ketone (PEEK), polyetherimide (PEI), polyamide imide (PAI), polyimide (PI), polyphenylene sulfone (PPSU), polyethersulfone (PES), polyphenylene sulfide (PSU), polyphenylene sulfide (PPS), and polyphthalamide (PPA), or engineering thermoplastics. 
     
     
       6. The process as claimed in  claim 5 , wherein said engineering thermoplastics are selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyamides. 
     
     
       7. The process as claimed in  claim 6 , wherein said polyamides are selected from the group consisting of PA9, PA46, and PPA. 
     
     
       8. The process as claimed in  claim 4 , wherein said high-temperature plastics comprise high-temperature thermosets. 
     
     
       9. The process as claimed in  claim 1 , comprising: 
       applying different layer thicknesses to different sides of the conductors or conductor bundles in at least one of steps S 3 , S 4 , S 5 , S 7 , and S 8 .  
     
     
       10. The process as claimed in  claim 1 , wherein S 2  heating of the substrate comprises electrical heating. 
     
     
       11. The process as claimed in  claim 10 , wherein electrical heating comprises induction electrical heating or resistance electrical heating. 
     
     
       12. The process as claimed in  claim 1 , wherein S 3  orienting comprises controlling the orientation of the conductor or conductor bundle with a control device of a spraying robot. 
     
     
       13. The process as claimed in  claim 1 , further comprising: 
       operating a plurality of spray guns simultaneously when said conductor of conductor bundle comprises a large conductor or conductor bundle.  
     
     
       14. The process as claimed in  claim 1 , wherein S 1  mounting comprises mounting with intermediate supports when said conductors or conductor bundles comprise large conductors or conductor bundles, to ensure reliable positioning. 
     
     
       15. The process as claimed in  claim 14 , further comprising: 
       moving away said intermediate supports automatically under the control of a control device of a spraying robot when said spray gun approaches said intermediate supports.  
     
     
       16. The process as claimed in  claim 1 , comprising: 
       controlling an applied layer thickness with a control device of a spraying robot, said controlling comprising controlling a powder-delivery device and a speed of movement of the spray gun.  
     
     
       17. The process as claimed in  claim 1 , wherein S 5  rotating comprises rotating the conductor or conductor bundle so that a further flat side of the conductor or conductor bundle is oriented perpendicular to the spray gun. 
     
     
       18. The process as claimed in  claim 1 , wherein S 6  changing the coating powder comprises changing either by exchanging a powder reservoir or exchanging an entire spraying installation including a powder reservoir, a powder-delivery device, and a spray gun. 
     
     
       19. The process as claimed in  claim 1 , wherein S 7  changing and coating comprises: 
       monitoring a surface temperature without contact; and  
       readjusting the substrate temperature in response to a recorded surface temperature.  
     
     
       20. The process as claimed in  claim 1 , further comprising: 
       after coating the conductor or conductor bundle has ended and after removal of the conductor or conductor bundle from the rotation and holding device, coating bar ends or coil eyelets which have been used as holding points for the rotation and holding device.  
     
     
       21. The process as claimed in  claim 1 , comprising: 
       when a relatively large layer thickness has been applied to the conductor or the conductor bundle, cooling the layers close to the substrate and outside spraying spot so that said layers solidify and no longer flow away.  
     
     
       22. The process as claimed in  claim 1 , wherein said coating powder for an external corona-discharge protection comprises a conductively filled powder. 
     
     
       23. The process as claimed in  claim 1 , wherein S 9  cooling comprises allowing the coated conductor or conductor bundle to cool. 
     
     
       24. A for producing a high-quality insulation for conductors or conductor bundles, comprising the steps of: 
       (S 1 ) prestrengthening the conductor or conductor bundle by winding a tape around said conductor or conductor bundle, said tape comprising a conductive or semiconductive layer;  
       (S 2 ) mounting a conductor or conductor bundle which is to be coated on a rotation and holding device;  
       (S 3 ) heating the conductor or conductor bundle to a predetermined substrate temperature;  
       (S 4 ) thermal spraying a liquid or plastic internal corona-discharge protection onto the heated substrate from a coating powder, the application layer thickness being approximately 0.05 to 0.2 mm,  
       (S 5 ) changing the coating powder into an insulant-filled powder;  
       (S 6 ) coating the conductor or conductor bundle with the insulant-filled powder in at least one pass on all sides of the conductor or conductor bundle as described in step S 4 ;  
       (S 7 ) carrying out steps S 5  and S 6  using a coating powder for an external corona-discharge protection; and  
       (S 8 ) cooling the coated conductor or conductor bundle and removing it from the rotation and holding device.